From Brazil (image top), through Bolivia (center), and stretching southward into Argentina (bottom), scores of fires were detected by the <a HREF="http://modis.gsfc.nasa.gov" target="outlink">Moderate Resolution Imaging Spectroradiometer</a> (MODIS) on NASA?s <a HREF="http://terra.nasa.gov" target="outlink">Terra</a> satellite on October 1, 2002. Fire locations are marked with red dots. Right of image center, the skies are so thick with smoke that the ground is barely visible. According to news reports, a hot, windy winter is exacerbating the normal burning season. These fires are the subject of intense study in a variety of scientific disciplines—everything from the social pressures that drive people to use fire as an agricultural tool, to the loss of biodiversity, to the impact on air quality and rainfall patterns. Sensor: Terra/MODIS.